Cerebroside sulfotransferase is a membrane-associated enzyme which catalyze the synthesis of the galactolipid sulfatide, a constituent of myelin. The enzyme protein has been purifiid from rat kidney and antibodies have been raised against it. The antibodies have been characterized and used for immunocytochemical studies in the kidney. Our goal is to purify cerebroside sulfotransferase from rat brain and to compare and contrast the properties of this enzyme with the properties of the protein from rat kidney. monoclonal antibodies will be made against the brain protein by the lymphocyte hybridoma technique of Mulstein and Kohler. The antibodies will be characterized and used to develop a radioimmunoassay for the enzyme protein, so that the appearance and turnover of this particular enzyme proein can be studied during myelinogenesis. Knowledge of the role of the enzyme in myelination may aid in the study of diseases in which myelin is perturbed.